Using a monochromatic display has been well known. However, monochromatic displays do not offer color adequate color type detail such as reds, greens and blue colors.
Displays using liquid crystals have been proposed of generating color displays. See for example, U.S. Pat. No. 5,359,345 and 5,724,062 to Hunter. However, these patents require arranging individual pixels in rows and corresponding columns, column 4, lines 36-39. The devices described can be expensive and complicated to manufacture, and can have a narrow angular view ranges with low brightness.
Additional display systems have been proposed with similar problems to those described above. See for example, U.S. Pat. No. 4,791,415 to Takahashi; U.S. Pat. No. 4,871,231 to Garcia, Jr.; U.S. Pat. No. 5,184,114 to Brown; U.S. Pat. No. 5,192,946 to Thompson et al.; and U.S. Pat. No. 5,317,348 to Knize.
Several patents have been proposed for panel displays using two-frequency upconversion fluorescence. See for example, U.S. Pat. Nos. 5,684,621; 5,764,403; 5,914,807; 5,943,160; and 5,956,172 all to Downing. The Downing ""403 patent appears to be the most relevant to the subject invention. Downing ""403 is primarily concerned with embodiments where the use of different layers for red, green and blue emitters, abstract, FIG. 6, and briefly describes some mixing of only crystal type materials in a single display media. However, for the single display media, Downing ""403 uses nanometer sized particles, column 4, lines 33+, column 9, lines 42-45, which would inherently be difficult to form, handle and disperse in a display medium.
Other known patents such as U.S. Pat. No. 5,003,179 to Pollack; U.S. Pat. No. 5,051,278 to Paz-Pujalt; U.S. Pat. No. 5,154,962 to Mertens et al.; U.S. Pat. No. 5,245,623 to McFarlane; U.S. Pat. No. 5,622,807 to Cutler; U.S. Pat. No. 5,846,684 to Paz-Pujalt et al. also fail to overcome the problems with the other patents described above.
The primary objective of this invention is provide an inexpensive medium for two and three dimensional displays.
The secondary objective of this invention is to provide a transparent polymer(plastic) containing particles doped with rare ions for use as display medium for two and three dimensional displays.
The third objective of this invention is to provide a medium for the up conversion of near infrared light to the visible for two and three dimensional displays.
The invention encompasses the up conversion and diode lasers operating at approximately 970 nm to develop displays in which a scanned and modulated beam of near infrared light causes visible light to be emitted from a display medium. A preferred embodiment of a display system of the subject invention uses a two and three dimensional display without the need of a vacuum tube nor any high voltage electronics. The novel display system offers significant improvements in the areas of display safety, cost, complexity and size over prior art systems.
Although near infrared diodes are relatively simple and inexpensive, the light is, of course not visible. Red, green and blue visible laser sources are complex and expensive and produce light that an observer sees as speckled. Therefore, the subject inventors have developed a display system that employs the simplicity of the diode laser and yet yields full color, high resolution, high brightness, speckle free images. The invention demonstrates that the diode laser light can be converted into red, green and blue visible light by the mechanism of up conversion in certain crystals.
Further objects and advantages of this invention will be apparent from the following detailed description of a presently preferred embodiment which is illustrated schematically in the accompanying drawings.